Assessing the Long-Term Impact of Irrigation-Induced Soil Salinization on Horticultural Productivity in the Hadejia-Nguru Wetlands Region of North East Nigeria

Irrigation-induced soil salinization is an insidious threat to the sustainability of irrigated horticultural production systems in the Hadejia-Nguru Wetlands of North East Nigeria, where extensive irrigation schemes supporting vegetable and cash crop production have operated for over three decades. Cumulative salt loading from inappropriate irrigation management practices poses a growing risk to the long-term productive capacity of these internationally important wetland agricultural systems. This dissertation assesses the 30-year trajectory of soil salinization across horticultural production zones of the Hadejia-Nguru Wetlands using a combination of remote sensing time series analysis, historical soil data reconstruction, and field soil survey. Electrical conductivity, sodium adsorption ratio, exchangeable sodium percentage, and aggregate soil quality indices were measured from 200 geo-referenced soil profiles. Crop yield data from administrative records were related to soil quality metrics using panel econometric modeling. Results demonstrate a statistically significant increasing trend in electrical conductivity over the observation period, with 35 percent of surveyed soils now exhibiting moderate to severe salinity constraints. Panel regression models estimate a 22 percent yield loss per unit increase in electrical conductivity in the affected zones. The study develops a spatially explicit soil salinization risk map and a long-term remediation strategy framework for the Hadejia-Nguru horticulture landscape. Keywords: soil salinization, irrigation, Hadejia-Nguru Wetlands, horticulture, long-term assessment